A federal judge in New York has ruled that the National Security Agency's mass collection of phone data is constitutional, rejecting a challenge brought by the American Civil Liberties Union.

U.S. District Judge William Pauley's decision came just 11 days after a district judge in Washington ruled the opposite - that the agency's "almost Orwellian" surveillance program is likely unconstitutional. The ruling raises the likelihood that the issue will be settled by the Supreme Court.

In his 54-page decision, Pauley said there is no evidence that the government has used any of the data collected for purposes other than "investigating and disrupting" terror attacks.